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Baruch Rinkevich - One of the best experts on this subject based on the ideXlab platform.

  • coupling astogenic aging in the colonial tunicate Botryllus schlosseri with the stress protein mortalin
    Developmental Biology, 2018
    Co-Authors: Amalia Rosner, Matan Oren, Oshrat Benhamo, Claudette Rabinowitz, Baruch Rinkevich
    Abstract:

    Abstract Botryllus schlosseri, a colonial marine invertebrate, exhibits three generations of short-lived astogenic modules that continuously grow and die throughout the colony's entire lifespan, within week-long repeating budding cycles (blastogenesis), each consisting of four stages (A-D). At stage D, aging is followed by the complete absorption of adult modules (zooids) via a massive apoptotic process. Here we studied in Botryllus the protein mortalin (HSP70s member), a molecule largely known for its association with aging and proliferation. In-situ hybridization and qPCR assays reveal that mortalin follows the cyclic pattern of blastogenesis. Colonies at blastogenic stage D display the highest mortalin levels, and young modules exhibit elevated mortalin levels compared to old modules. Manipulations of mortalin with the specific allosteric inhibitor MKT-077 has led to a decrease in the modules’ growth rate and the development of abnormal somatic/germinal morphologies (primarily in vasculature and in organs such as the endostyle, the stomach and gonads). We therefore propose that mortalin plays a significant role in the astogeny and aging of colonial modules in B. schlosseri, by direct involvement in the regulation of blastogenesis.

  • Botryllus schlosseri and Botrylloides leachii (Chordata, Ascidiacea) have not been recorded in the Red Sea
    Marine Biodiversity, 2014
    Co-Authors: Eitan Reem, Baruch Rinkevich
    Abstract:

    Two botryllid species, Botryllus schlosseri and Botrylloides leachii are listed in a recent literature review on the ascidian species inventory from the Red Sea (Shenkar, Mar Biodiv 42:459–469, 2012). However, a detailed literature search does not reveal any scientific documentation for the existence of these species in the Red Sea.

  • Population genetics of the invasive ascidian Botryllus schlosseri from South American coasts
    Marine Ecology Progress Series, 2010
    Co-Authors: Rachel Ben-shlomo, Eitan Reem, Jacob Douek, Baruch Rinkevich
    Abstract:

    The cosmopolitan colonial ascidian Botryllus schlosseri, most likely a Mediterranean Sea and European Atlantic species, is one of the known human-mediated invaders of coastal marine communities. Whereas numerous populations spreading along the Northern Hemisphere coasts have been intensively studied for various population genetics parameters, the data available on the South- ern Hemisphere populations is sporadic, based on few and erratic field collections. By using 5 microsatellite loci, we studied gene diversity and possible introduction routes of 4 B. schlosseri populations on the east and west South American coasts. A Hardy-Weinberg exact test for all loci and all populations demonstrated a highly significant heterozygote deficiency. Analyses revealed high gene diversity in the Chilean populations of the west coast, whereas the maximal number of alleles per locus, the highest percentages of natural chimeras and private alleles and the highest levels of variability were observed in the Argentinean population of the east coast. Results further suggest that each of the Chilean populations was founded by a few genotypes. Comparing the genetic identities of South and North American B. schlosseri populations showed extensive dissimilarities, with hardly any common alleles shared, suggesting distinct B. schlosseri clades based on molecular biology data.

  • population genetics of the invasive ascidian Botryllus schlosseri from south american coasts
    Marine Ecology Progress Series, 2010
    Co-Authors: Rachel Benshlomo, Eitan Reem, Jacob Douek, Baruch Rinkevich
    Abstract:

    The cosmopolitan colonial ascidian Botryllus schlosseri, most likely a Mediterranean Sea and European Atlantic species, is one of the known human-mediated invaders of coastal marine communities. Whereas numerous populations spreading along the Northern Hemisphere coasts have been intensively studied for various population genetics parameters, the data available on the South- ern Hemisphere populations is sporadic, based on few and erratic field collections. By using 5 microsatellite loci, we studied gene diversity and possible introduction routes of 4 B. schlosseri populations on the east and west South American coasts. A Hardy-Weinberg exact test for all loci and all populations demonstrated a highly significant heterozygote deficiency. Analyses revealed high gene diversity in the Chilean populations of the west coast, whereas the maximal number of alleles per locus, the highest percentages of natural chimeras and private alleles and the highest levels of variability were observed in the Argentinean population of the east coast. Results further suggest that each of the Chilean populations was founded by a few genotypes. Comparing the genetic identities of South and North American B. schlosseri populations showed extensive dissimilarities, with hardly any common alleles shared, suggesting distinct B. schlosseri clades based on molecular biology data.

  • bs cadherin in the colonial urochordate Botryllus schlosseri one protein many functions
    Developmental Biology, 2007
    Co-Authors: Amalia Rosner, Ayelet Voskoboynik, Claudette Rabinowitz, Elizabeth Moiseeva, Baruch Rinkevich
    Abstract:

    Botryllus schlosseri is a colonial urochordate composed of coexisting modules of three asexually derived generations, the zooids and two cohorts of buds, each at disparate developmental stage. Functional zooids are replaced weekly by the older generation of buds through a highly synchronized developmental cycle called blastogenesis (which is, in turn, divided into four major stages, A to D). In this study, we examined the mode of expression of BS-cadherin, a 130-kDa transmembrane protein isolated from this species, during blastogenesis. BS-Cadherin is expressed extensively in internal organs of developing buds, embryos, ampullae and, briefly, in the digestive system of zooids at early blastogenic stage D (in contrast to low mRNA expression at this stage). In vitro trypsin assays on single-cell suspensions prepared from blastogenic stage D zooids, confirmed that BS-cadherin protein is expressed on cell surfaces and is, therefore, functional. BS-Cadherin expression is also upregulated in response to various stress conditions, such as oxidative stress, injury and allorecognition. It plays an important role in colony morphogenesis, because siRNA knockdown during D/A blastogenic transition causes chaotic colonial structures and disrupts oocytes homing onto their bud niches. These results reveal that BS-cadherin protein functions are exerted through a specific spatiotemporal pattern and fluctuating expression levels, in both development/regular homeostasis and in response to various stress conditions.

Loriano Ballarin - One of the best experts on this subject based on the ideXlab platform.

  • functional amyloidogenesis in immunocytes from the colonial ascidian Botryllus schlosseri evolutionary perspective
    Developmental and Comparative Immunology, 2019
    Co-Authors: Nicola Franchi, Francesca Cima, Loriano Ballarin, Anna Peronato, Annalisa Grimaldi, Rossana Girardello, Magda De Eguileor
    Abstract:

    Abstract Cytotoxic morula cells (MCs) and phagocytes are the circulating immunocytes of the colonial ascidian Botryllus schlosseri: Both these cells can synthesise amyloid fibrils, supporting the idea that physiological amyloidogenesis is involved in inflammation and modulation of immune responses. Intriguingly, amyloid of B. schlosseri immunocytes is made of two different proteins. MCs, the first cells to sense non-self and involved in the allorejection reaction between contacting genetically incompatible colonies, use melanin encapsulation as the principal method to fight non-self. They release amyloid fibrils formed by p102 protein that allow the packaging and deposit of melanin and other toxic molecules nearby the invader or in the contact region of incompatible colonies. Phagocytes release amyloid-based extracellular traps when challenged with microbes: their amyloid fibrils harbour BsAPP, an orthologue of the vertebrate amyloidogeneic protein APP. This strategy of immune response, present also in human neutrophils, allows phagocytes to block and engulf bacteria and fungi.

  • data on four apoptosis related genes in the colonial tunicate Botryllus schlosseri
    Data in Brief, 2016
    Co-Authors: Nicola Franchi, Lucia Manni, Filippo Schiavon, Francesca Ballin, Loriano Ballarin
    Abstract:

    The data described are related to the article entitled “Recurrent phagocytosis-induced apoptosis in the cyclical generation change of the compound ascidian Botryllus schlosseri” (Franchi et al., 2016) [1]. Four apoptosis-related genes, showing high similarity with mammalian Bax (a member of the Bcl-2 protein family), AIF1 (apoptosis-inducing factor-1), PARP1 (poly ADP ribose polymerase-1) and IAP7 (inhibitor of apoptosis-7) were identified from the analysis of the trascriptome of B. schlosseri. They were named BsBax, BsAIF1, BsPARP1 and BsIAP7. Here, their deduced amino acid sequence were compared with known sequences of orthologous genes from other deuterostome species together with a study of their identity/similarity.

  • Data on four apoptosis-related genes in the colonial tunicate Botryllus schlosseri
    Elsevier, 2016
    Co-Authors: Nicola Franchi, Lucia Manni, Filippo Schiavon, Francesca Ballin, Loriano Ballarin
    Abstract:

    The data described are related to the article entitled “Recurrent phagocytosis-induced apoptosis in the cyclical generation change of the compound ascidian Botryllus schlosseri” (Franchi et al., 2016) [1]. Four apoptosis-related genes, showing high similarity with mammalian Bax (a member of the Bcl-2 protein family), AIF1 (apoptosis-inducing factor-1), PARP1 (poly ADP ribose polymerase-1) and IAP7 (inhibitor of apoptosis-7) were identified from the analysis of the trascriptome of B. schlosseri. They were named BsBax, BsAIF1, BsPARP1 and BsIAP7. Here, their deduced amino acid sequence were compared with known sequences of orthologous genes from other deuterostome species together with a study of their identity/similarity. Keywords: Sequence databases, Alignments, BLAST analysis, Botryllus schlosseri, Apoptosis-related transcripts, Bax, AIF1, PARP1, IAP

  • life history and ecological genetics of the colonial ascidian Botryllus schlosseri
    Zoologischer Anzeiger – A Journal of Comparative Zoology, 2015
    Co-Authors: Francesca Cima, Fabio Gasparini, Filippo Schiavon, Nicola Franchi, Loriano Ballarin, Federico Caicci, Francesca Rigon, Lucia Manni
    Abstract:

    The colonial ascidian Botryllus schlosseri is a cosmopolitan, marine filter feeder, introduced as a laboratory research organism in the 1950s. Currently, it is widely used in many laboratories to investigate a variety of biological questions. Recently, it has become a species of concern, as it is an invasive species in many coastal environments. Here, we review studies on the geographical distribution of the species, sexual and asexual reproduction in the field, tolerance to temperature, salinity and anthropogenic activity, polychromatism, enzymatic polymorphism, and the genetic basis of pigmentation. Studying the relationship between genetic polymorphism and the adaptation of B. schlosseri to environmental stress is a challenge of future research and will improve our understanding of its evolutionary success and invasive potential.

  • insights on cytotoxic cells of the colonial ascidian Botryllus schlosseri
    ISJ-Invertebrate Survival Journal, 2015
    Co-Authors: Nicola Franchi, Loriano Ballarin, Francesca Cima
    Abstract:

    Morula cells (MCs) represent the most abundant circulating hemocyte of the compound ascidian Botryllus schlosseri. They are cytotoxic cells involved in the rejection reaction between contacting, genetically incompatible colonies. Upon the recognition of foreign substances, they degranulate and release their content, which contribute to the cell death along the contact borders. A major role in MCrelated cytotoxicity is exerted by the enzyme phenoloxidase (PO) that converts polyphenol substrata to quinones which, then, polymerize to form melanins. During this reaction, reactive oxygen species are formed which are the cause of MC-related cytotoxicity. Here, we carried out new analyses to investigate further the nature of MC content and its role in cytotoxicity. Results confirm that PO is located inside MC vacuoles together with arylsulfatase, iron and polyphenols/quinones, the latter probably representing ready-to-use cytotoxic molecules, deriving from the oxidation of DOPAcontaining proteins. In addition, small DOPA-containing peptides, called tunichromes, are also present inside MCs. MC degranulation and PO-mediated cytotoxicity are prevented by secretion inhibitors and by H89 and calphostin C. The observation that PO activity is always detectable in MCs in the absence of protease treatment, and its inhibition by sulfites and sulfates, suggest a non-classical pathway of PO modulation in botryllid ascidians.

Anthony W De Tomaso - One of the best experts on this subject based on the ideXlab platform.

  • the biology of the extracorporeal vasculature of Botryllus schlosseri
    Developmental Biology, 2019
    Co-Authors: Delany Rodriguez, Shane Nourizadeh, Anthony W De Tomaso
    Abstract:

    Abstract The extracorporeal vasculature of the colonial ascidian Botryllus schlosseri plays a key role in several biological processes: transporting blood, angiogenesis, regeneration, self-nonself recognition, and parabiosis. The vasculature also interconnects all individuals in a colony and is composed of a single layer of ectodermally-derived cells. These cells form a tube with the basal lamina facing the lumen, and the apical side facing an extracellular matrix that consists of cellulose and other proteins, known as the tunic. Vascular tissue is transparent and can cover several square centimeters, which is much larger than any single individual within the colony. It forms a network that ramifies and expands to the perimeter of each colony and terminates into oval-shaped protrusions known as ampullae. Botryllus individuals replace themselves through a weekly budding cycle, and vasculature is added to ensure the interconnection of each new individual, thus there is continuous angiogenesis occurring naturally. The vascular tissue itself is highly regenerative; surgical removal of the ampullae and peripheral vasculature triggers regrowth within 24–48 h, which includes forming new ampullae. When two individuals, whether in the wild or in the lab, come into close contact and their ampullae touch, they can either undergo parabiosis through anastomosing vessels, or reject vascular fusion. The vasculature is easily manipulated by direct means such as microinjections, microsurgeries, and pharmacological reagents. Its transparent nature allows for in vivo analysis by bright field and fluorescence microscopy. Here we review the techniques and approaches developed to study the different biological processes that involve the extracorporeal vasculature.

  • gonad development and hermaphroditism in the ascidian Botryllus schlosseri
    Molecular Reproduction and Development, 2017
    Co-Authors: Delany Rodriguez, Susannah H Kassmer, Anthony W De Tomaso
    Abstract:

    : The colonial ascidian Botryllus schlosseri is an ideal model organism for studying gonad development and hermaphroditism. B. schlosseri has been reared in laboratories for over half a century, and its unique biology allows investigators to probe the processes of germ cell migration and gonad formation, resorption, and regeneration. Following metamorphosis, colonies of B. schlosseri show a synchronized and sequential fertility program that, under standard laboratory conditions, begins with a juvenile stage with no visible gonads and subsequently develops testes at 9 weeks followed later by the production of oocytes-thus resulting in hermaphroditic individuals. The timing of oocyte production varies according to the season, and adult B. schlosseri colonies can cycle among infertile and both male and hermaphrodite fertile states in response to changing environmental conditions. Thus, these acidians are amenable to studying the molecular mechanisms controlling fertility, and recent genomic and transcriptomic databases are providing insight to the key genes involved. Here, we review the techniques and approaches developed to study germ cell migration and gonad formation in B. schlosseri, and include novel videos showing processes related to oocyte ovulation and sperm discharge. In the future, this valuable invertebrate model system may help understand the mechanisms of gonad development and regeneration in a chordate. Mol. Reprod. Dev. 84: 158-170, 2017. © 2016 Wiley Periodicals, Inc.

  • Balancing selection on allorecognition genes in the colonial ascidian Botryllus schlosseri.
    Developmental and Comparative Immunology, 2016
    Co-Authors: Marie L. Nydam, Emily E. Stephenson, Claire E. Waldman, Anthony W De Tomaso
    Abstract:

    Abstract Allorecognition is the capability of an organism to recognize its own or related tissues. The colonial ascidian Botryllus schlosseri , which comprises five genetically distinct and divergent species (Clades A-E), contains two adjacent genes that control allorecognition: fuhc sec and fuhc tm . These genes have been characterized extensively in Clade A and are highly polymorphic. Using alleles from 10 populations across the range of Clade A, we investigated the type and strength of selection maintaining this variation. Both fuhc genes exhibit higher within-population variation and lower population differentiation measures (F ST ) than neutral loci. The fuhc genes contain a substantial number of codons with >95% posterior probability of d N /d S  > 1. fuhc sec and fuhc tm also have polymorphisms shared between Clade A and Clade E that were present prior to speciation (trans-species polymorphisms). These results provide robust evidence that the fuhc genes are evolving under balancing selection.

  • aging in the colonial chordate Botryllus schlosseri
    Invertebrate Reproduction & Development, 2015
    Co-Authors: Roma Munday, Daryl A Taketa, Adam D. Langenbacher, Alessandro Di Maio, Brian P Braden, Delany Rodriguez, Susannah H Kassmer, Anthony W De Tomaso
    Abstract:

    What mechanisms underlie aging? One theory, the wear-and-tear model, attributes aging to progressive deterioration in the molecular and cellular machinery which eventually lead to death through the disruption of physiological homeostasis. The second suggests that life span is genetically programmed, and aging may be derived from intrinsic processes which enforce a non-random, terminal time interval for the survivability of the organism. We are studying an organism that demonstrates both properties: the colonial ascidian, Botryllus schlosseri. Botryllus is a member of the Tunicata, the sister group to the vertebrates, and has a number of life history traits which make it an excellent model for studies on aging. First, Botryllus has a colonial life history, and grows by a process of asexual reproduction during which entire bodies, including all somatic and germline lineages, regenerate every week, resulting in a colony of genetically identical individuals. Second, previous studies of lifespan in genetically...

  • Botryllus schlosseri allorecognition tackling the enigma
    Developmental and Comparative Immunology, 2015
    Co-Authors: Daryl A Taketa, Anthony W De Tomaso
    Abstract:

    Allorecognition has been well-studied in the context of vertebrate adaptive immunity and recognition of the Major Histocompatibility Complex (MHC), which is the central event of vertebrate immune responses. Although allorecognition systems have been identified throughout the metazoa, recent results have shown that there is no apparent conservation or orthologous relationship between the mechanisms underlying this phenomenon in different organisms. Thus the origin of the vertebrate adaptive immune system as well as these other complex recognition systems is a complete mystery. This review will focus on allorecognition in Botryllus schlosseri, a basal chordate which undergoes a natural transplantation reaction following contact between two individuals, and, analogous to vertebrates, is controlled by a single locus. We will summarize each of the known candidate genes within this locus and their potential roles in allorecognition, and speculate on how these findings may in fact be revealing potential functional relationships between disparate allorecognition systems.

Irving L Weissman - One of the best experts on this subject based on the ideXlab platform.

  • Botryllus schlosseri an emerging model for the study of aging stem cells and mechanisms of regeneration
    Invertebrate Reproduction & Development, 2015
    Co-Authors: Ayelet Voskoboynik, Irving L Weissman
    Abstract:

    The decline of tissue regenerative potential with the loss of stem cell function is a hallmark of mammalian aging. We study Botryllus schlosseri, a colonial chordate which exhibits robust stem cell-mediated regeneration capacities throughout life. Larvae, derived by sexual reproduction and chordate development, metamorphose to clonal founders that undergo weekly formation of new individuals by budding from stem cells. Individuals are transient structures which die through massive apoptosis, and successive buds mature to replicate an entire new body. As a result, their stem cells, which are the only self-renewing cells in a tissue, are the only cells which remain through the entire life of the genotype and retain the effects of time. During aging, a significant decrease in the colonies’ regenerative potential is observed and both sexual and asexual reproductions will eventually halt. When a parent colony is experimentally separated into a number of clonal replicates, they frequently undergo senescence simu...

  • identification of a novel gene involved in asexual organogenesis in the budding ascidian Botryllus schlosseri
    Developmental Dynamics, 2005
    Co-Authors: Diana J Laird, Wenteh Chang, Irving L Weissman, Robert J Lauzon
    Abstract:

    Development via regeneration or budding shares some known genetic pathways with embryogenesis, but no concerted effort has been made to identify genes unique to asexual development. We have identified a novel gene that plays a role in cyclical bud formation and asexual organogenesis in the colonial ascidian Botryllus schlosseri. Athena mRNA is transcribed at high levels during the 24- to 36-hr interval of programmed cell death and new bud initiation at the conclusion of the budding cycle (takeover). Knockdown of Athena by RNAi and antisense morpholinos induced defects in the development of new buds ranging from retardation in growth and abnormal organogenesis to hollow buds lacking organs. As genetic intervention in this organism has not been possible, this study establishes the use of RNAi and morpholinos in Botryllus as well as describing the knockdown phenotype of a new gene. Developmental Dynamics 234:997–1005, 2005. © 2005 Wiley-Liss, Inc.

  • Identification of a novel gene involved in asexual organogenesis in the budding ascidian Botryllus schlosseri.
    Developmental dynamics : an official publication of the American Association of Anatomists, 2005
    Co-Authors: Diana J Laird, Wenteh Chang, Irving L Weissman, Robert J Lauzon
    Abstract:

    Development via regeneration or budding shares some known genetic pathways with embryogenesis, but no concerted effort has been made to identify genes unique to asexual development. We have identified a novel gene that plays a role in cyclical bud formation and asexual organogenesis in the colonial ascidian Botryllus schlosseri. Athena mRNA is transcribed at high levels during the 24- to 36-hr interval of programmed cell death and new bud initiation at the conclusion of the budding cycle (takeover). Knockdown of Athena by RNAi and antisense morpholinos induced defects in the development of new buds ranging from retardation in growth and abnormal organogenesis to hollow buds lacking organs. As genetic intervention in this organism has not been possible, this study establishes the use of RNAi and morpholinos in Botryllus as well as describing the knockdown phenotype of a new gene.

  • hsp70 genes and historecognition in Botryllus schlosseri implications for mhc evolution
    Hereditas, 2004
    Co-Authors: Melinda Bonnie Fagan, Irving L Weissman
    Abstract:

    : The colonial protochordate Botryllus schlosseri possesses a historecognition system which has long invited comparison to the vertebrate MHC. Upon contact, colonies either fuse or reject one another in a manner resembling graft acceptance or rejection in vertebrates. This response is controlled by a single highly polymorphic genetic region, the FuHC locus. Colonial protochordates such as B. schlosseri are among the closest relatives of the vertebrate lineage, and therefore may possess a recognizable MHC homologue. Since linkage between heat shock protein 70 (HSP70) genes and MHC appears to be conserved within the vertebrate lineage, we have analyzed HSP70 genes from B. schlosseri as a first step toward isolating the historecognition locus. Two HSP70 genes (HSP70.1 and HSP70.2) have been cloned and sequenced, and exhibit 93.6% sequence identity within the predicted coding regions. The B. schlosseri genes share a number of characteristics with vertebrate MHC-linked HSP70 genes: Northern blotting and sequence analysis suggest that the protochordate genes are cytoplasmically-expressed heat-inducible members of the HSP70 gene family (FAGAN and WEISSMAN 1996). However, unlike vertebrate MHC-linked HSP70 genes, HSP70.1 and HSP70.2 are not closely linked (FAGAN and WEISSMAN 1997). Furthermore, neither is closely linked to the locus determining historecognition (FAGAN and WEISSMAN 1997). These results do not support the hypothesis that the B. schlosseri FuHC locus is an MHC homolog. A discussion of the implications of these results for evolution of the vertebrate MHC is included.

  • effects of allogeneic contact on life history traits of the colonial ascidian Botryllus schlosseri in monterey bay
    The Biological Bulletin, 2003
    Co-Authors: Nanette E Chadwickfurman, Irving L Weissman
    Abstract:

    The formation of chimeric colonies following allogeneic contact between benthic invertebrates may strongly affect colony fitness. Here we show that, in a field population of the colonial ascidian Botryllus schlosseri in Monterey Bay, California, more than 20% of all colonies occur in allogeneic contact with conspecifics. We experi- mentally assessed the effects of allogeneic contact on the following life-history traits under natural field conditions: growth, age and size at first reproduction, and egg produc- tion (fecundity). When compared with isolated colonies, and in some cohorts also with colonies that rejected alloge- neic neighbors, colonies that fused with neighbors incurred reduced fitness in terms of most life-history traits measured. We propose that one of the benefits of precise allorecogni- tion is that, in fused colonies, it limits the unit of selection to chimeric individuals composed of closely related kin.

Jacob Douek - One of the best experts on this subject based on the ideXlab platform.

  • population genetics of the invasive ascidian Botryllus schlosseri from south american coasts
    Marine Ecology Progress Series, 2010
    Co-Authors: Rachel Benshlomo, Eitan Reem, Jacob Douek, Baruch Rinkevich
    Abstract:

    The cosmopolitan colonial ascidian Botryllus schlosseri, most likely a Mediterranean Sea and European Atlantic species, is one of the known human-mediated invaders of coastal marine communities. Whereas numerous populations spreading along the Northern Hemisphere coasts have been intensively studied for various population genetics parameters, the data available on the South- ern Hemisphere populations is sporadic, based on few and erratic field collections. By using 5 microsatellite loci, we studied gene diversity and possible introduction routes of 4 B. schlosseri populations on the east and west South American coasts. A Hardy-Weinberg exact test for all loci and all populations demonstrated a highly significant heterozygote deficiency. Analyses revealed high gene diversity in the Chilean populations of the west coast, whereas the maximal number of alleles per locus, the highest percentages of natural chimeras and private alleles and the highest levels of variability were observed in the Argentinean population of the east coast. Results further suggest that each of the Chilean populations was founded by a few genotypes. Comparing the genetic identities of South and North American B. schlosseri populations showed extensive dissimilarities, with hardly any common alleles shared, suggesting distinct B. schlosseri clades based on molecular biology data.

  • Population genetics of the invasive ascidian Botryllus schlosseri from South American coasts
    Marine Ecology Progress Series, 2010
    Co-Authors: Rachel Ben-shlomo, Eitan Reem, Jacob Douek, Baruch Rinkevich
    Abstract:

    The cosmopolitan colonial ascidian Botryllus schlosseri, most likely a Mediterranean Sea and European Atlantic species, is one of the known human-mediated invaders of coastal marine communities. Whereas numerous populations spreading along the Northern Hemisphere coasts have been intensively studied for various population genetics parameters, the data available on the South- ern Hemisphere populations is sporadic, based on few and erratic field collections. By using 5 microsatellite loci, we studied gene diversity and possible introduction routes of 4 B. schlosseri populations on the east and west South American coasts. A Hardy-Weinberg exact test for all loci and all populations demonstrated a highly significant heterozygote deficiency. Analyses revealed high gene diversity in the Chilean populations of the west coast, whereas the maximal number of alleles per locus, the highest percentages of natural chimeras and private alleles and the highest levels of variability were observed in the Argentinean population of the east coast. Results further suggest that each of the Chilean populations was founded by a few genotypes. Comparing the genetic identities of South and North American B. schlosseri populations showed extensive dissimilarities, with hardly any common alleles shared, suggesting distinct B. schlosseri clades based on molecular biology data.

  • identification of immune relevant genes in histoincompatible rejecting colonies of the tunicate Botryllus schlosseri
    Developmental and Comparative Immunology, 2007
    Co-Authors: Matan Oren, Zvi Fishelson, Jacob Douek, Baruch Rinkevich
    Abstract:

    The colonial ascidian Botryllus schlosseri manifests a unique allorecognition system that is controlled by a single histocompatibility haplotype, the Fu/HC locus. When two allogeneic incompatible colonies come into direct contact, they develop inflammatory-like rejection lesions, called points of rejection (POR). While screening for differentially expressed genes during POR formation, we developed and analyzed a cDNA library of expressed sequence tags (ESTs) with 1693 unique ESTs that were clustered and assembled into 217 contigs and 1476 singlets. About 51% of these ESTs showed high similarity (E-value ⩽0.005) to known database sequences, of which 123 matches were identified as immune-relevant genes encoding for stress proteins, pattern recognition receptors and complement proteins, proteases and protease inhibitors, cell adhesion and coagulation proteins, cytokine-related proteins, programmed cell death and proteasome-associated proteins. This first EST wide-screening analysis of the Botryllus allorecognition effector arm reveals a complex innate immune system, hallmarked by a whole genome response to allorecognition challenge.

  • genetic structure of Botryllus schlosseri tunicata populations from the mediterranean coast of israel
    Marine Ecology Progress Series, 2003
    Co-Authors: Jacob Douek, Menachem Goren, Caiqing Mo, Baruch Rinkevich
    Abstract:

    Botryllus schlosseri, a subtidal cosmopolitan tunicate species, is abundant in many rocky shores along the Mediterranean and other European seas. A highly polymorphic microsatellite locus (BS-811) elucidated Botryllus population genetics in 3 localities along the Israeli coast (at Shikmona, Caesarea and Michmoret, 12 to 36 km apart from each other, north to south, respectively) during 8 seasonal samplings (2 yr). Four other loci were studied only in the Michmoret population. The analy- sis on 1156 scorable colonies revealed a high number of alleles per locus (up to 15 to 38 alleles), unique alleles for each population (8 to 13 alleles per locus), high heterozygous deficiency, rapid sea- sonal changes in allele frequencies at all sites, and the existence of natural chimeric colonies. Locus BS-811, which was studied in all 3 localities, revealed 34 to 40 alleles per locality, and a total of 64 alleles, of which 48% were unique to one or other of the localities. Only 24 colonies from the 1156 studied were heterozygous on this locus. These results are discussed together with recent outcomes from B. schlosseri populations sampled in New Zealand, the east and west coasts of the USA and the Adriatic Sea, Croatia.

  • genetic structure of Botryllus schlosseri tunicata populations from the mediterranean coast of israel
    Marine Ecology Progress Series, 2003
    Co-Authors: Jacob Douek, Menachem Goren, Caiqing Mo, Baruch Rinkevich
    Abstract:

    Botryllus schlosseri, a subtidal cosmopolitan tunicate species, is abundant in many rocky shores along the Mediterranean and other European seas. A highly polymorphic microsatellite locus (BS-811) elucidated Botryllus population genetics in 3 localities along the Israeli coast (at Shikmona, Caesarea and Michmoret, 12 to 36 km apart from each other, north to south, respectively) during 8 seasonal samplings (2 yr). Four other loci were studied only in the Michmoret population. The analy- sis on 1156 scorable colonies revealed a high number of alleles per locus (up to 15 to 38 alleles), unique alleles for each population (8 to 13 alleles per locus), high heterozygous deficiency, rapid sea- sonal changes in allele frequencies at all sites, and the existence of natural chimeric colonies. Locus BS-811, which was studied in all 3 localities, revealed 34 to 40 alleles per locality, and a total of 64 alleles, of which 48% were unique to one or other of the localities. Only 24 colonies from the 1156 studied were heterozygous on this locus. These results are discussed together with recent outcomes from B. schlosseri populations sampled in New Zealand, the east and west coasts of the USA and the Adriatic Sea, Croatia.